# Challenges Remember the rules for this are - Try to use only the information given up to this point in this book. - Try not to give up until you've given it a solid attempt ## Challenge 1. Write a `Shoe` class. Give each shoe a `name` field and a `quality` field. Have these fields be initialized inside of a constructor. ```java,editable enum Quality { SUPA_FINE, FINE, SUB_FINE } // CODE HERE void main() { Shoe nike = new Shoe("Nikes", Quality.SUB_FINE); IO.println( "SHOE: " + nike.name + ", " + nike.quality ); Shoe moccasin = new Shoe("Moccasins", Quality.SUPA_FINE); IO.println( "SHOE: " + moccasin.name + ", " + moccasin.quality ); } ``` ## Challenge 2. Add a new `price` field to the `Shoe` class you wrote above. Add a new constructor which accepts a third argument to set the `price`. Keep the old two argument constructor around as well. When that one is used set `price` to `null`. Hint: Use `Double` to represent a nullable price. ```java,editable enum Quality { SUPA_FINE, FINE, SUB_FINE } // CODE HERE void main() { Shoe jays = new Shoe("Air Jordans", Quality.FINE, 130.0); IO.println( "SHOE: " + jays.name + ", " + jays.quality + ", $" + jays.price ); Shoe nike = new Shoe("Nikes", Quality.SUB_FINE, 25); IO.println( "SHOE: " + nike.name + ", " + nike.quality + ", $" + nike.price ); Shoe moccasin = new Shoe("Moccasins", Quality.SUPA_FINE); IO.println( "SHOE: " + moccasin.name + ", " + moccasin.quality + ", $" + moccasin.price ); } ``` ## Challenge 3. Alter the `Shoe` class so that the `price` field is final. Alter its constructors so that if they are given a negative value they throw an exception instead of finishing normally. Keep in mind that while `null` is allowed (you might not know the price) a negative number wouldn't be. Nobody is paying you to take their shoes.[^holes] ```java,editable enum Quality { SUPA_FINE, FINE, SUB_FINE } // CODE HERE void main() { Shoe jays = new Shoe("Air Jordans", Quality.FINE, 130.0); IO.println( "SHOE: " + jays.name + ", " + jays.quality + ", $" + jays.price ); Shoe nike = new Shoe("Nikes", Quality.SUB_FINE, 25); IO.println( "SHOE: " + nike.name + ", " + nike.quality + ", $" + nike.price ); Shoe moccasin = new Shoe("Moccasins", Quality.SUPA_FINE); IO.println( "SHOE: " + moccasin.name + ", " + moccasin.quality + ", $" + moccasin.price ); Shoe shouldCrash = new Shoe("Base Ball Cleats", Quality.SUPA_FINE, -10); } ``` [^holes]: If they do, you are going to dig holes in the desert in search of treasure that rightfully belongs to you. ## Challenge 4. If you haven't yet, rewrite your `Shoe` constructors so only one of them actually sets fields and the other just delegates to that one. ```java,editable enum Quality { SUPA_FINE, FINE, SUB_FINE } // CODE HERE void main() { Shoe jays = new Shoe("Air Jordans", Quality.FINE, 130.0); IO.println( "SHOE: " + jays.name + ", " + jays.quality + ", $" + jays.price ); Shoe nike = new Shoe("Nikes", Quality.SUB_FINE, 25); IO.println( "SHOE: " + nike.name + ", " + nike.quality + ", $" + nike.price ); Shoe moccasin = new Shoe("Moccasins", Quality.SUPA_FINE); IO.println( "SHOE: " + moccasin.name + ", " + moccasin.quality + ", $" + moccasin.price ); Shoe shouldCrash = new Shoe("Base Ball Cleats", Quality.SUPA_FINE, -10); } ```